Chemistry Review

• Chemistry– Atoms, molecules, &

compounds– Inorganic Molecules– Organic Molecules

• Biological Macromolecues

– Lipids– Carbohydrates– ___________– Nucleic Acids

Chemical Principles

• What is the smallest unit of matter that enters into chemical reactions?

• Chemistry = interactions between ____ and molecules

H H

O

Atomic Structure• Electrons – negatively charged subatomic particles

circling a nucleus• Nucleus – contains neutrons and protons

– Neutrons – uncharged particles– Protons – positively charged particles

Atomic Structure• Element = single type

of atom• Atomic Number =

number of protons in nucleus

• Atomic Mass (atomic weight) = sum of masses of protons, neutrons, and electrons

Isotopes

• Isotopes - differ in number of ________ in their nuclei

• Stable isotopes• Unstable isotopes

–Release energy during radioactive decay

168 O 17

8 O 188 O

Will this effect the overall charge?

Electron Configurations• Electrons determine

an atom’s chemical behavior

• Occupy electron shells• Valance electrons –

the missing or extra electrons in this shell.

• Atoms combine to complete the outermost shell.

Electronic Configurations

Table 2.2.1

Electron Configurations

Figure 2.3

Electron Configurations

• How many valance electrons does this atom want to give up or acquire?

Chemical Bonds

• A compound contains different kinds of atoms.

H2O

• The forces holding atoms in a compound are chemical bonds.

Name the different types of chemical bonds.

Chemical Bonds

• Ionic Bonds• ________ Bonds

–Nonpolar –Polar

• Hydrogen bonds – weak forces that combine with polar covalent bonds

Ionic Bonds• Two atoms with vastly different electronegativities.• Atoms give or receive electrons to form IONS

– positively (cation) charged– or negatively (anion) charged

Ionic Bonds• Ionic bonds are attractions between ions of

opposite charge. • One atom loses electrons and another

gains electrons.

Figure 2.2b

Covalent Bonds

• Covalent bond – sharing of a pair of electrons by two atoms

Covalent Bonds

Nonpolar Covalent Bonds

• Atoms with similar electronegativities• Equal sharing of electrons• No poles exist

Polar Covalent Bonds

• Unequal sharing of electrons– due to significantly different electronegativities

• Most important polar covalent bonds involve hydrogen

–Allows for hydrogen bonding

Polar Covalent Bonds

Figure 2.7a

Hydrogen Bonds

• Electrical attraction between –partially charged H+ & full or partial negative

charged molecule• Weaker than covalent bonds but ________ for life

–Many help to stabilize 3-D shapes of large molecules

Hydrogen Bonds

Chemical Reactions• The making or breaking of chemical bonds• Involve reactants and products• Three categories of chemical reactions

–Synthesis reactions–Decomposition reactions–Exchange reactions

Synthesis Reactions

• Formation of larger, more complex molecules• Important type – dehydration synthesis

–Water molecule formed• Require energy (endothermic)• All the synthesis reactions in an organism are called anabolism

A + B ABAtom, ion,

or molecule A

→Atom, ion,

or molecule BNew molecule

AB

Decomposition Reactions

• Break bonds within larger molecules to form smaller atoms, ions, and molecules

• Release energy (exothermic)• Common type – hydrolysis• All the decomposition reactions in an organism are

called catabolism

A + BABAtom, ion,

or molecule A

→Atom, ion,

or molecule BNew molecule

AB

Breaksdown into

Chemical Reactions

The sum total of all chemical reactions is an organism is called _______?

Exchange Reactions

• Part synthesis and part decompositionreactions

• Involve endothermic and exothermic steps• Atoms moved from one molecule to another

NaCl + H2O→NaOH + HCl

Reversible Reactions

• Can readily go in either direction.• Each direction may need special conditions.

←→

Heat

A + B ABWater

Inorganic Compounds: Water

• Polar molecule– Remains liquid across wide

range of temperatures– Water molecules are cohesive →

surface tension

Figure 2.4a

• Excellent Solvent– Polar

substances dissociate, forming solutes

Inorganic Compounds: Water

Figure 2.5

Inorganic Compounds: Water

• Participates in many chemical reactions

• H+ and OH−

Inorganic Compounds: Water

• Hydrogen bonding between water molecules makes water a temperature ______.– Can absorb significant

amounts of energy without changing temperature

Figure 2.4b

Acids and BasesAn acid is a substance that dissociates into one or more H+.

HCl → H+ + Cl−

A base is a substance that dissociates into one or more OH−.

NaOH → Na+ + OH−

Salts

• A salt is a substance that dissociates into cations and anions, neither of which is H+

or OH−.

NaCl → Na+ + Cl−

Acid-Base Balance

• The amount of H+ in a solution is expressed as pH.

• pH = −log[H+]• Increasing [H+], increases acidity.• Increasing [OH−] increases alkalinity.• Most organisms grow best between pH 6.5

and 8.5.

Acid-Base Balance

Figure 2.7

• Carbon skeleton = chain of carbon atoms in an organic molecule.

• Functional groups give an organic compound its chemical properties.

Organic Compounds

Table 2.3.1

Organic Compounds

• Small organic molecules can combine into large macromolecules.

• Basic subunit = monomer• Chain of monomers = polymer• Macromolecules are polymers consisting

of many small repeating molecules.

Organic Compounds

• Monomers join by dehydration synthesis or (condensation reactions).

Figure 2.8

Important Biological Molecules

• Organic compounds - always contain carbon and hydrogen.

• Inorganic compounds typically lack carbon. • Macromolecules in a cell

– Lipids– Carbohydrates– ________– Nucleic Acids

• Monomers – basic building blocks of macromolecules

• Not composed of monomers • All are hydrophobic (non polar)

–Insoluble in water• Are the primary components of cell membranes.

• Consist of C, H, and O.• Four groups

–Fats–Phospholipids–Waxes–Steroids

Lipids

Fats

Figure 2.15

Figure 2.16

Phospholipids

Figure 2.16

Phospholipids

Major membrane component

Waxes

• Contain one long-chain fatty acid covalently linked to long-chain alcohol by ester bond

• Completely ________ in water; lack hydrophilic head

Figure 2.17

Steroids

Part of cell membraneUsed for signaling

Carbohydrates

• Organic molecules • Composed of carbon, hydrogen, and oxygen

(CH2O)n

• Important for structure and as an energy source

Carbohydrates

• Types–Monosaccharides–Disaccharides–Polysaccharides

Monosaccharides

= simple sugars

Figure 2.18a

Monosaccharides

Figure 2.18b

Monosaccharides

Figure 2.18c

Disaccharides

•Disaccharides = two monosaccharides joined in a dehydration reaction.

•Disaccharides can be broken down by ___?_____.

Figure 2.19

Disaccharides

Figure 2.19

Carbohydrates• Polysaccharides consist of tens or hundreds

of monosaccharides joined through dehydration synthesis.

• Starch, glycogen, dextran, and cellulose are polymers of glucose that are covalently bonded differently.

• Chitin is a polymer of two sugars repeating many times.

Polysaccharides

Figure 2.20

Polysaccharides

Figure 2.20

• Mostly composed of carbon, hydrogen, oxygen, nitrogen, and sulfur

• Functions–Structure–Enzymatic catalysis–Regulation–Transportation–Defense and offense

Proteins

Amino Acids• The monomers that make up proteins• Most organisms use only 21 amino acids to build proteins

• Side groups affect interactions• A covalent bond (peptide bond) formed between amino acids by dehydration synthesis reaction

Amino Acids

Figure 2.21

Protein Structure•The primary structure is a polypeptide chain

•The secondary structure occurs when the amino acid chain folds and coils in a regular helix or pleats.

Figure 2.24

Figure 2.24

Protein Structure

•The tertiary structure from disulfide bonds, hydrogen bonds, and ionic bonds between amino acids in the chain.

•The quaternary structure consists of two or more polypeptides.

Proteins – Form follows Function

Modified Proteins

• Conjugated proteins consist of amino acids and other organic molecules:• Glycoproteins = proteins + sugars• Nucleoproteins = proteins + nucleic acids• Lipoproteins = proteins + lipids

Nucleic Acids

• DNA and RNA vital as genetic material of organisms

• RNA helps form polypeptides

Nucleotides

• The monomers that make up nucleic acids• Composed of three parts

–Phosphate group–Pentose sugar – deoxyribose or ribose–One of five cyclic nitrogenous bases

• Adenine (A)• Guanine (G)• Cytosine (C)• Thymine (T)• Uracil (U)

Nucleic Acid Structure

Figure 2.26

Nucleic Acid Structure• H bonds form between C and G and between T and A in DNA

–U and A in RNA• DNA is double stranded in most cells and viruses

–Two strands are complementary–Two strands are antiparallel

Nucleic Acid Function

• DNA is genetic material of all organisms and of many viruses

• Carries instructions for synthesis of RNA and proteins → controls synthesis of all molecules in an organism

Figure 2.27

ATP

ATP• Is made by dehydration synthesis.• Is broken by hydrolysis to liberate useful

energy for the cell.